Study On Pretreatment Of Lignocelluloses And Its Degradation Mechanism

As the environmental pollution and excessive consumption of non-renewable fossil resources,more and more scientists are beginning to look for a kind of renewable resources.At present,the biomass resources is the only renewable alternative resources in the existing resources.Using biomass to produce bio-based products,not only can reduce the reliance on fossil fuel resources,to ensure the safety of human energy,at the same time,also can reduce pollution of the environment.However,pretreatment of biomass is an important link in the production of bio-based products.Different kinds of biomass which have different composition and structure need to adopt different pretreatment methods.In order to find a suitable pretreatment process,this topic mainly aimed at corn stalks and sorghum stalk and evaluated various pretreatment methods.Three different pretreatment methods were performed in this article.The first part of this work was the study of high temperature ethanol pretreatment on the corn stalk.In this pretreatment,the concentration of ethanol was 48%.Meantime,the effect of different temperature and reaction time on the performance were investigated.According to the results of physicochemical characterizations and the enzymatics saccharification ability of different pretreated samples,the optimal condition was 160 ?,20 min and reaction systems containing 0.5%sulfuric acid.The second part was compared the acid-alkali with alkali-acid two-step pretreatment for sweet sorghum fiber on enzymatic saccharification ability.Different concentration of acid or alkali and different sequence of acid and alkali were studied.The results indicated that the effect of acid-alkali and alkali-acid two-step pretreatments on the sweet sorghum fiber were different and the total sugar production from alkali-acid pretreatment was larger than that from acid-alkali pretreatment.The third part of this work was studied the sulphuric acid pretreatment on different parts of corn stalk for second generation ethanol production.The results indicated that hemicelluloses in different parts of corn stalk were largely removed and the pretreated samples showed different crystallinity and compositions.Compared with other samples,the corn cob had higher cellulose content and better effect of enzymatic hydrolysis.For the corn cob the glucose yield was 94.2%and the ethanol production was 24.0 g/L which is the highest in the five samples.While for the corn flower,the glucose yield was 86.0%and the ethanol production was only 17.1 g/L which is the lowest in the five samples.